| Seaham to Mangualde | 1,026.82 mi (1,652.51 km) |
| Seaham to Marco de Canavezes | 993.56 mi (1,598.98 km) |
| Seaham to Marinha Grande | 1,100.11 mi (1,770.46 km) |
| Seaham to Massama | 1,171.11 mi (1,884.72 km) |
| Seaham to Matosinhos | 1,001.70 mi (1,612.09 km) |
| Seaham to Mealhada | 1,051.02 mi (1,691.45 km) |
| Seaham to Melgaco | 933.48 mi (1,502.29 km) |
| Seaham to Melres | 1,004.92 mi (1,617.26 km) |
| Seaham to Mira | 1,051.83 mi (1,692.75 km) |
| Seaham to Miranda do Corvo | 1,068.23 mi (1,719.16 km) |
| Seaham to Mirandela | 960.36 mi (1,545.56 km) |
| Seaham to Mogadouro | 964.94 mi (1,552.92 km) |
| Seaham to Moimenta da Beira | 999.77 mi (1,608.98 km) |
| Seaham to Moita | 1,174.02 mi (1,889.40 km) |
| Seaham to Moncao | 939.63 mi (1,512.19 km) |
